Our vacation is sorely lacking. Anything less than 5:15 a day is a fail IMO. I also believe a 6th week is achievable:

20 years: 6 weeks
15 years: 5 weeks
10 years: 4 weeks

This is big value. Every 25 hours in additional vacation is roughly a 2.5% increase in compensation based on a 1000 hour year. Even more if you choose to fly less!